Influence of Lignin Content on Morphology and Properties of Poly(Lactic Acid)/Lignin Composite Films

In this work, PLA/lignin composite films have been developed for packaging films. The composite films were prepared by a solution casting method. The lignin was prepared from black liquor from the paper industry, by extracting with acetic acids at 50°C. The lignin contents in PLA matrix were 0.5, 1, 3 and 5 phr. Fourier-transformed infrared spectroscopy (FTIR) analysis demonstrated similar structure of lignin precipitation when compared with the standard lignin. The addition of lignin reduced the tensile strength of PLA/lignin films, whereas the composite film at 1 phr of lignin was more elongation than neat PLA. Scanning electron microscopy (SEM) micrographs showed the roughness surface and voids in the composite films, except 1 phr and 5 phr of lignin with a better interface between PLA and lignin. UV-Vis analysis indicated reduced light transmission with increasing lignin contents in UV region.